1. Field of the Invention
This invention relates to compositions and methods for attracting, trapping and/or killing crop pests from Euschistus species known as stink bugs.
1. Description of the Prior Art
The genus Euschistus is the largest of the genera in the so-called stink bug family Pentatomidae (order Hemiptera: suborder Heteroptera). Over 60 Euschistus species have been described, including 18 from North America. Several Euschistus species are among the most common members of the family in the western hemisphere and, to many people, these large brown insects are recognized as the stink bug.
Euschistus adults are strong fliers and often migrate to a succession of maturing crops where they feed on developing fruits or seeds. The immature bugs usually disperse from the initial point of attack, thereby spreading the infestation. As with other kinds of stink bugs, Euschistus adults and immatures suck sap or oil through hypodermic-like mouthparts, thus inconspicuously damaging the most valuable portion of the crop. Their feeding also indirectly reduces yield and seed quality by transmitting diseases. In the absence of food or with the onset of winter, adults are able to hibernate and resume attack the following season.
Various Euschistus species attack a wide range of fruit, field crops, vegetables, and nut crops. In the western United States the consperse stink bug, E. conspersus, is a major pest of tomatoes and also causes "catfacing" of apples, peaches, pears, grapes, and other fruits. During years of high E. conspersus populations, cotton and seed alfalfa yields in California have been seriously reduced. East of the Rocky Mountains three other Euschistus species are serious agricultural pests of field, vegetable, fruit, and nut crops: E. servus, the brown stink bug; E. variolarius, the onespotted stink bug; and E. tristigmus, the dusky stink bug. One or more of these Euschistus species frequently coexist with the green stink bugs, Acrosternum hilare and Nezara viridula, to form a complex that, along with the corn earworm, is the most damaging of the soybean pod feeders in the southern U.S. Although stink bug damage to soybean is less severe in more northerly regions of the U.S., the widespread use of reduced tillage crop systems has vastly increased the threat of E. servus and E. viriolarius to corn. This threat has arisen in fields under a soybean/corn or wheat/corn rotation because the brown and onespotted stink bugs overwinter in soybean and wheat stubble, then feed on emerging corn seedlings in the spring. A single stink bug can cause irrevocable damage to a corn plant in less than 24 hours. In Central and South America other species of Euschistus bugs are important pests. For example, E. heros is one of the three major stink bug pests of soybean in Brazil.
Outbreaks of Euschistus and other stink bugs are difficult to control because the bugs can migrate into a field and irreversibly damage a crop before they are noticed. Population build-ups that go undetected my lead to infestations of later maturing crops or outbreaks the following season. Moreover, several stink bug species usually coexist at varying abundances from region to region and year to year, further complicating monitoring and control strategies.
Although the use of insecticides has increased the quality and quantity of crop yields, there are serious disadvantages to the use of presently available insecticides. The toxicity to humans and animals is high. Additionally, they are not readily degraded and may thus pollute the environment. Therefore, reducing or eliminating the amount of toxic insecticides used in the management of insect pests is desirable. It is an object of the present invention to provide compositions and methods by which the amounts of pesticide may be reduced or eliminated in eradicating Euschistus species stink bugs.
Attractant pheromones have recently been identified for several species of predatory and plant-feeding stink bugs. F. Warnaar [Phytochemistry, Vol. 20, (1981), pp. 89-91] disclosed the mass spectra (MS) of methyl (2E,4Z)-decadienoate and methyl (2E,4E)-decadienoate, both of which closely resemble the MS of the E. conspersus male-specific compound.
Additionally, there has been reported a strong synergism between methyl E,Z-2,4-decadienoate and chalcogran at attracting the bark beetle, Pityogenes chalcographus [Byers, et al., Naturwissenschaften, Vol. 75, (1988), pp. 153-155]. The reference does not indicate a utility for the attraction and/or management of insects of the Euschistus species.